Grip and percussion myotonia

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Myotonia is a disorder of the muscle membrane causing a kind of sustained muscle contraction, an inability to relax. (1, 2) Tone is normal when the muscles are relaxed, but contraction produces a temporary involuntary tonic persistence of muscle contraction with slow relaxation. Myotonia typically improves with repeated contractions, the warm up phenomenon, and may worsen in the cold or after prolonged rest. Paradoxical myotonia worsens after repetitive contraction.

In grip myotonia, the patient has difficulty letting go of an object after gripping it strongly. Percussion myotonia is elicited by tapping on the muscle.

For an example of eyelid myotonia see Eyelid_myotonia.(3) For an example of myotonia of the tongue see tongue myotonia. (4) For an example of myotonia of the toe extensors see toe extensor myotonia.(5)

Myotonia occurs in myotonic dystrophy types 1 and 2, the sodium channelopathies (hyperkalemic periodic paralysis and paramyotonia congenita), chloride channelopathies (myotonia congenita) and other conditions.

Video legend. Patient demonstrating percussion myotonia of the thenar muscles and grip myotonia first compared to normal then showing both hands at once.

Video courtesy of Dr. Paul E. Barkhaus, Medical College of Wisconsin.


1. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.

2. Roberts K, Kentris M. Myotonia. 2022 May 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32644698.

3. Adhikari S, Statland J, Farmakidis C. Eyelid myotonia and face stiffness in skeletal muscle sodium channelopathy. RRNMF Neuromuscular Journal 2021:2;71-72.

4. Wang ZJ, Huang XS. Images in clinical medicine. Myotonia of the tongue. N Engl J Med. 2011 Oct 13;365(15):e32.

5. Mankodi A, Grunseich C. Toe-extension myotonia in myotonic dystrophy type 1. Neurology. 2015 Jul 14;85(2):203.